1. Field of the Invention
This invention concerns a device for mixing particulate material and liquid, and particularly for mixing water and absorbent material which is reactive with gaseous pollutants in flue gases and which, during cleaning of the flue gases, is to be introduced into these gases in a moistened state in order to convert the gaseous pollutants into separable dust, said device comprising an elongate container having two lengthwise side walls and being arranged essentially horizontally in its lengthwise extension, an inlet for the introduction of particulate material into the container, a liquid spraying means for spraying liquid over the particulate material in the container, an agitator in said container, said agitator consisting of at least one rotary shaft which extends in the longitudinal direction of the container and on which are mounted, at an angle, a plurality of axially spaced-apart discs through the centres of which the shaft extends, an outlet for discharging material mixed with liquid from the container, and a fluidizing means adapted to fluidize the particular material in the container during the mixing operation.
2. Description of Background Art
When gaseous pollutants, such as sulphur dioxide, are to be separated from flue gases, the gases are conducted through a contact reactor in which particulate absorbent material reactive with the gaseous pollutants is introduced in a moistened state into the flue gases in order to convert the gaseous pollutants to separable dust. The flue gases are then conducted through a dust separator, in which dust is separated from the flue gases and from which the thus-cleaned flue gases are drawn off. Part of the dust separated in the dust separator is conducted to a mixer, where it is mixed and moistened with water, whereupon it is recycled as absorbent material by being introduced into the flue gases along with an addition of fresh absorbent. Slaked lime (calcium hydroxide) is generally used as the fresh absorbent.
One prior-art device of the kind defined in the introduction is shown in WO 96/16727. The container of the prior-art device has a rear end in which the inlet is located, and a front end in which the outlet is located. When the prior-art device is used as a mixing device in which the above-described mixing of absorbent material and water is performed, the front end of the container is inserted in a flue-gas channel through which the flue gases containing the gaseous pollutants are conducted. The outlet, which thus also is disposed in the flue-gas channel, is an overflow means formed by the lengthwise side walls in the part of the container inserted in the channel being lower than in the container part located outside the channel.
In the WO 96/16727, the prior-art device is disadvantageous because of the projection of the container into the flue-gas channel, which may cause disturbance of the gas flow therein and make it difficult to obtain an even distribution of moistened material across the channel cross-section, particularly in the case of large cross-sectional areas.